An important development in natural gas production in recent decades, at least in the continental United States, has been the improvement of hydraulic fracturing techniques for stimulating production from previously uneconomically tight formations. For some years, the fastest growing segment of gas production has been from shales or very silty zones that previously have not been considered economic. The current areas of increasing activity include the Barnett Shale, the Haynesville Shale, the Fayetteville Shale, the Marcellus Shale and other shale or shaley formations.
There are a variety of down hole tools used in the completion and/or production of hydrocarbon wells such as bridge plugs, flow back plugs, ball drop plugs and the like. In the past, these have all been tools specially designed for a single purpose. It is no exaggeration to say that the future of natural gas production in the continental United States is from heretofore uneconomically tight gas bearing formations, many of which are shales or shaley silty zones. Accordingly, a development that allows effective frac jobs at overall lower costs is important.
Disclosures of interest relative to this invention are found in U.S. Pat. Nos. 2,714,932; 2,756,827; 3,282,342; 3,291,218; 3,393,743; 3,429,375; 3,554,280; 5,311,939; 5,419,399; 6,769,491; 7,021,389 and 7,350,582 along with printed patent application 2008/0060821.